The invention discloses an apparatus for centering and aligning vessels in preparation for performing an operation on the vessels such as applying a label to them. One method of centering bottles in preparation for labeling, for example, requires using a bottle that has a recess in its bottom. When the bottle is supported on a plate carried by a rotary bottle transport table, the bottle is rotated until a detent registers with the recess in the bottle to assure that the bottle is centered and aligned in the proper orientation.
German Patent DE-PS 33 08 489 discloses a device that performs this function. In the patented device, the vessel is rotated on a support plate until a spring loaded engagement detent aligns with the recess at the bottom of the bottle under the influence of a rotatably supported centering ring which is caused to rotate by means of a friction drive, while the plate that supports the bottom of the bottle is prevented from rotating. The inherent disadvantage is that the bottle rotating force that must be transferred from the centering ring to the outer edge of the bottle bottom must be transferred by a relatively small funnel shaped centering surface, opposing the significant frictional force between the bottom of the bottle and the plate on which it is supported. Sometimes the centering surface of the centering ring will slip undesirably past the bottle contour or there can be undesirable slippage between the friction surface and the support ring that bears the centering ring, so that the alignment detent does not always reliably engage in the recess at the bottom of the bottle. A further disadvantage of the patented device is that it is not suitable for aligning vessels which have a recess or recesses in the sidewalls of the bottles as well as in the bottom.
German Patent DE-PS 24 19 133 also discloses a device for aligning cylindrical bottles, wherein the bottles are elevated by a centering cone with a control device as the bottles pass through an alignment zone and are rotated until an alignment cam or detent engages the recess in the bottle. This is done either by using a large area friction device acting directly on the bottles or by using a friction wheel connected to the centering cone. In the embodiment first mentioned, problems arise during operation as a result of the presently poor dimensional tolerances of the bottles and their frequently wet surfaces which result in slippage so that alignment is not always accurate. Another disadvantage is that the area on the bottle which is subject to frictional engagement differs with the shape of the bottles so that the friction device must be changed when a bottle style is changed. Use of the device is limited to bottles which have a conical bottom and no centering can take place from the outer contour of the bottom of the bottle. The most disadvantageous feature of the device, however, is its size and the space which it occupies resulting from the necessity for vertical control of the centering cone. The size is so great that the device barely fits into the space allowed on the rotating bottle transport table of a modern high capacity labeling machine. This is especially true in designs where the centering cone is rotated using an additional friction wheel.
Another alignment and centering device is described in U.S. Pat. No. 4,280,612, particularly FIG. 11, in which rotation required for alignment of the bottle is also accomplished with a friction wheel drive unit. This device also cannot be used for labeling or other bottle handling operations using a conventional rotating bottle transport table, but instead requires a bottle table with considerably more elaborate control and gearing mechanisms.